Running rich, can't pull codes

[tmielnichuk]

Running rich, can't pull codes Update!

Hi everyone,

Here's the details:

89 SHO will start when cold, but will run extremely rough and runs very rich. So rich that it creates black spots on the pavement under the tailpipes. It is NOT burning oil. If I tap the gas lightly it stumbles and almost dies. If I try to move the car it will stumble and stall out. The car will run ok after warming up for about five minutes. If it is at idle and I tap the gas after it has warmed up the revs will dip THEN rise as usual.

I tried to pull the codes but the computer refuses to give up the goods. No CEL and it won't even run the tests. No cycling of the sensors\valves at all. The bulb isn't burn out on the CEL. I can't run either the KOER or KOEO test.

What would make it run so rich? Is the ECU screwed? Would the car even run with a "fried" computer? Are the O2 sensors screwed? Could this be a knock sensor problem?

No-one in this area seems to have a SHO that I can borrow an ECU from to swap it temporarily.

Any thoughts on how to trouble shoot this problem would be great.

Here is a list of parts that have been replaced recently:
Throttle position sensor
Water Pump
Crank position sensor
Water temp senders
Fuel Pump
Fuel Filter
alternator
starter motor (Didn't do the solenoid though)
plugs
wires
valve cover gaskets and plug well seals
IAB
probably some other little things that I can't remember.

I do know that the relay for the rad fan is conked out so I wired the fan to a rocker switch in the dash. Would the rest of that relay unit be causing any problems if the other relays are damaged?

Sorry for the long post but I am stumped.


Thanks for all the help guys and girls!

 

[SHO--ripper]

Could be the MAF or 02's. I doubt the MAF would cause such problems, but for such a cheap part why not swap it out. If i remember correctly the then that controls the fan also has something to do with the fuel. IRCM=Ignition Relay Control Module. How's your DIS? I've got a computer and IRCM that i could sell you if you want to try them. $40 shipped for both

 

[tmielnichuk]

Hey SHO--ripper,

I'd be interested in the IRCM and computer for the $40 shipped... I'm assuming they are known to be working? Email me at [email protected] and we can set up the details.

Could the O2 sensors cause this problem?

I think the computer MUST be shot because I can't even get a code or anything out of it.

Anything else I should check out??????

 

[AutoSHO]

Does the CEL illuminate when you first turn the key on to start the car?

 

[tmielnichuk]

When the key is in the run position the CEL is on.

 

[rangerj]

How are you trying to check the codes? Are you using a scanner, or using a jumper wire and the CE light method? Please forgive me if I have insulted you, that is not the intention.

If you have hooked up the jumper wire correctly, and you cannot get either the KOEO ot the KOER test to cycle it is very possible, if not likely, that part of the internal memory in the ECU is gone. The computer has a "fail-safe" or "limp-in mode" it goes into whenever the computer is not getting all the information it is programmed to expect (very oversimplified explanation).

Anyways, the fail-safe mode is a rich mixture mode, as a lean mixture could cause high temperatures, burn valves, burn a hole in the top of a piston, etc.
Have you tried disconnecting the ECU connection (60 pin) at the firewall, checking for connection problems such as corrosion or loose pins, and reconnecting it? Just a thought.

Yes, the car can run with a partial failure of the ECU. Think of it as having a disk with one bad segment. With the bad segment everthing works, but poorly.

I think you are on the right track. Again, I have no intention of insulting you with my questions. I'm just trying to think out loud with you on this perplexing problem. The 2 parts for $40 is a good deal, go for it! rangerj

 

[bradman]

I had similar symptoms from my 89 before I changed the O2 sensors and the ECT sensor. They were both throwing codes and causing the car to run very rich. Keep trying to get those codes. Also, check all your wiring for loose connections and/or bad grounds.

 

[tmielnichuk]

Ranger J,

No insult taken at all. I have been using the old jumper method of getting my codes out. I'm pretty sure that the ECU must be failing in the way you described. The power wire coming from the starter solenoid to the battery chaffed through last summer and shorted out, causing al sorts of fuses to blow, not to mention screwing my starter motor and scaring the crap out of me!

Anyway, I'm off to the bank to change some of my funny looking Canadian money into your funny looking American money so I can buy that new ECU and IRCM.

Thanks for all your help guys! I'll update this post when I get the parts.

 

[tmielnichuk]

Parts in, car still screwed

Hi Guys,

I got the parts, got the parts in, still runs like a pile of crap. RICH as ****.

The good news is that the new ECU and relay IRCM seem to work just fine (thanks Chris!)

I was able to pull some codes tonight after I skinned my knuckles gettinf everything back together:

21, 85, 66, 95 All KOEO

I wasn't able to get the car to stay running through the KOER test.

I think that at least I've got a good ECU now (I can pull codes!)

I think the worst of the bunch is the 66 (maf voltage too low). When the car is running and I unplug the Maf, nothing changes in the way the car runs. Does this indicate a crapped out MAF? I'm tired of chasing gremlin after gremlin on this car.

If I'm doing my research right the codes are as such:

21 ECT out of self-test range.
85 CANP (Canister Purge) circuit failure. (I removed the stupid thing, not to worry)
66 MAF sensor input is less than minimum voltage.
95 Fuel pump secondary circuit failure.

How would this all relate to my problems of the car running rich? Will a bad 02 sensor only show on a KOER?

Thanks again guys!

 

[40BelowSummer]

start with changing the ECT sensor it will make it run rich as a bitch, hehe. and since its free and doesnt take long try cleaning the MAF as well

 

[AutoSHO]

As he said, ECT will make it run very rich. Try that (under $20) first!

 

[40BelowSummer]

As he said, ECT will make it run very rich. Try that (under $20) first!

$17.99 + tax from autozone
PN: SU201

wait...do they have auto zone in BC?

oh well youll find it

 

[projectSHO89]

Before changing anything, look for the +5V reference voltage on each of those sensors that the KOEO test flagged. My bet ithat either it is missing or there is an open ground connection. In any event, it is good practice to check before swapping parts.

See the electrical diagrams in the Electrical forum for the color codes and connections.

Disconnect the MAF BEFORE starting the engine to force the computer into FFEM. Thern test it. Same for the ECT.

Make sure the IAC is plugged in. Most common cause of failure to idle.

Steve

 

[ckinart]

21 ECT out of self-test range.
85 CANP (Canister Purge) circuit failure. (I removed the stupid thing, not to worry)
66 MAF sensor input is less than minimum voltage.
95 Fuel pump secondary circuit failure.

Were you able to let the engine run long enough to warm up to regular operating temperature before you ran the codes? If you run the codes on a cold engine, you'll get the "ECT out of range" code every time. However, as others have said, it could definitely be causing your problem and is relatively cheap and easy to replace.

Have you checked your fuel pressure?

 

[SHO--ripper]

I second the fuel pressure. Mabye a shot fuel pump or clogged filter?
BTW i'm glad you got the parts

 

[tmielnichuk]

drivin

Hi guys,

Tons of fuel pressure, I might just change the stupid filter again (did it about 6 months ago) and have cleaned the MAF with electical connections cleaner spray. The car was warmed up to full temp when I ran the tests. I replaced the ECT and the dummy gague sender about a year and a half ago. Is it possible (dunno how) that by putting a small peice of silicone tape on the threads that I am causing problems? I didn't want any coolant leaks so I applied a small amount of that white tape to the threads on both sensors before I screwed them in. I don't really want to change them out just for that, but I hate driving at over a $1.00 a Litre for gas when my car runs so rich.

The car does run a bit better now that the ircm and ecu are in, and the MAF cleaning might have made a bit of a difference but it still runs very rich (good luck punching the throttle or using low rpm up a hill!) so I'd like to get this sucker fixed once and for all. It's been soooooo long since I had a tip-top running SHO I forget what it feels like to drive "normally".

I am in the middle of moving into a new house this weekend so I am short on time and money to keep fixing this car.

Thanks for the help again guys.

Could the o2 sensor possibly (I mean at all) cause my problems?

How much does a new MAF cost if it is the culprit?

Are there directions anywhere for testing the voltage situation on the ECT and MAF? I have a basic voltage meter from Radio Shack.

I want to rule out parts before I start buying more chasing this thing down.

 

[ckinart]

Tons of fuel pressure

Perhaps too much pressure?

Corey

 

[tmielnichuk]

Brand new fuel pressure regulator is on there already, no way for the rail to see too much pressure and cause it to run rich as far as I know.

Does anybody have any thoughts on the previous questions about the sealant tape on the threads of the sensors? I might just replace the ECT anyway because it is pretty inexpensive, but if I can just peel the tape off.....

 

[Mr Anonymous]

Both the ECT and the gauge sender should have come with a dry pipe thread sealant already on them and shouldn't require any additional sealant. If they've been removed and the sealant has worn off, then I would recommend using a liquid pipe thread sealant instead of teflon tape.

 

[tmielnichuk]

Would this tape casue my ECT to fail or not function properly, causing my car to run rich? I'm thinking it's not grounding properly?

The low coolant light is on all the time even though it is topped up and the coolant level "float" is working properly.

Help!

If the DIS is faulty will it cause these problems?

Can anyone tell me where to find testing instructions for the DIS, MAF and ECT?

Thanks!